Why pathologists and oncologists should know about tumour-infiltrating lymphocytes (TILs) in triple-negative breast cancer: an Australian experience of 139 cases.

The presence of increased tumour infiltrating lymphocytes (TILs) is established as a positive prognostic factor in triple-negative breast cancer (TNBC). The majority of studies have examined the role of TILs in predicting response to chemotherapy, but their role as a general prognostic marker in TNBC is unclear. Moreover, there is a lack of consensus in the literature regarding a suitable cut-off point by which to stratify patients into prognostic groups. Therefore, we sought to confirm the prognostic value of TILs in an independent cohort of unselected TNBCs, and to determine an appropriate cut-off point by which to stratify TIL scores into prognostically significant categories. We used the International TILs Working Group (ITWG) methodology to assess the density of stromal TILs in our cohort of 139 TNBC patients undergoing curative resection at our institution. The percentage TILs scores were categorised first into three groups: low (0-10%), intermediate (15-50%), and high (55-100%). A second binary variable was also created by separating cases into low TILs (≤50%) and high TILs (>50%) groups. Using the three-tiered system, mean disease-free survival was 156, 99 and 94 months for the high, intermediate and low TILs groups, respectively (p=0.030). However, no statistically significant improvement was observed for overall survival. Using the two-tiered system, statistically significant improvements in both overall survival (p=0.030) and disease-free survival (p=0.010) were observed. This survival benefit remained statistically significant in multivariate analyses (p=0.010, p=0.014). We conclude that TILs scored using the ITWG system and dichotomised at a cut-off score of 50%, are a powerful predictor of all-cause and disease-free survival in TNBC regardless of chemotherapy treatment.

Inflammatory Myofibroblastic Tumors of the Female Genital Tract Are Under-recognized: A Low Threshold for ALK Immunohistochemistry Is Required.

Inflammatory myofibroblastic tumor (IMT) of the female genital tract is under-recognized. We investigated the prevalence of ALK-positive IMT in lesions previously diagnosed as gynecologic smooth muscle tumors. Immunohistochemistry (IHC) for ALK was performed on tissue microarrays of unselected tumors resected from 2009 to 2013. Three of 1176 (0.26%) "leiomyomas" and 1 of 44 (2.3%) "leiomyosarcomas" were ALK IHC positive, confirmed translocated by fluorescence in situ hybridization (FISH) and therefore more appropriately classified as IMT. On review significant areas of all 4 tumors closely mimicked smooth muscle tumors morphologically, but all showed at least subtle/focal features suggesting IMT. Recognizing that the distinction between IMT and leiomyoma/leiomyosarcoma can be subtle, we then reviewed 1 hematoxylin and eosin slide from each patient undergoing surgery for "leiomyoma" from 2014 to 2017 and selected cases for ALK IHC with a low threshold. Of these, 30 of 571 (5.3%) underwent IHC. Two were confirmed to be IHC positive and FISH rearranged. Of the 6 IMTs, only 1 tumor with a previous diagnosis of leiomyosarcoma, an infiltrative margin and equivocal necrosis, metastasized. Of note it demonstrated a less aggressive clinical course compared with most metastatic leiomyosarcomas (alive with disease at 6 y). The patient was subsequently offered crizotinib to which she responded rapidly. In conclusion, IMTs may closely mimic gynecologic smooth muscle tumors. IMTs account for at least 5 of 1747 (0.3%) tumors previously diagnosed as leiomyoma and 1 of 44 (2.3%) as leiomyosarcoma. These tumors may be recognized prospectively with awareness of subtle/focal histologic clues, coupled with a low threshold for ALK IHC.

Lessons learnt from implementation of a Lynch syndrome screening program for patients with gynaecological malignancy.

Despite a trend towards universal testing, best practice to screen patients presenting with gynaecological malignancy for Lynch syndrome (LS) is uncertain. We report our institutional experience of a co-ordinated gynaecological LS screening program. All patients with endometrial carcinoma or carcinosarcoma, or gynaecological endometrioid or clear cell carcinomas undergo reflex four panel immunohistochemistry (IHC) for MLH1, PMS2, MSH2 and MSH6 followed by cascade somatic hypermethylation analysis of the MLH1 promoter locus for dual MLH1/PMS2 negative tumours. On the basis of these results, genetic counselling and targeted germline mutation testing is then offered to patients considered at high risk of LS. From 1 August 2013 to 31 December 2015, 124 patients were screened (mean age 64.6 years). Thirty-six (29.0%) demonstrated abnormal MMR IHC: 26 (72.2%) showed dual loss of MLH1/PMS2, five (13.9%) dual loss of MSH2/MSH6, three (8.3%) isolated loss of MSH6, and two (5.6%) isolated loss of PMS2. Twenty-five of 26 (96.1%) patients with dual MLH1/PMS2 loss demonstrated MLH1 promoter methylation. Therefore, 11 (8.9%) patients screened were classified as high risk for LS, of whom nine (81.8%) accepted germline mutation testing. Three (2.4% of total screened) were confirmed to have LS, two with germline PMS2 and one with germline MSH2 mutation. Massive parallel sequencing of tumour tissue demonstrated somatic mutations which were concordant with the IHC results in the remainder. Interestingly, the one MLH1/PMS2 IHC negative but not hypermethylated tumour harboured only somatic MLH1 mutations, indicating that universal cascade methylation testing in MLH1/PMS2 IHC negative tumours is very low yield and could be reconsidered in a resource-poor setting. In conclusion, universal screening for LS in patients presenting with gynaecological malignancy using the algorithm described above identified LS in three of 124 (2.4%) of our population. Only three of nine (33.3%) patients considered at high risk for LS by combined IHC and hypermethylation analysis were proven to have LS. Only one of the LS patients was less than 50 years of age and none of these patients would have been identified had more restrictive Amsterdam or Bethesda criteria been applied.

Loss of BAP1 expression is very rare in peritoneal and gynecologic serous adenocarcinomas and can be useful in the differential diagnosis with abdominal mesothelioma.

Gynecologic and primary peritoneal serous carcinoma may be difficult to distinguish from abdominal mesotheliomas clinically, morphologically, and immunohistochemically. BAP1 double-hit inactivation and subsequent loss of protein expression have been reported in more than half of all abdominal mesotheliomas. We therefore sought to investigate the expression of BAP1 in serous carcinoma and explore its potential utility as a marker in the differential diagnosis with mesothelioma. We searched the computerized database of the Department of Anatomical Pathology, Royal North Shore Hospital, Australia, for all cases of gynecologic and peritoneal serous carcinomas and mesotheliomas diagnosed between 1998 and 2014. Immunohistochemistry for BAP1 was then performed on tissue microarray sections. Cases with completely absent nuclear staining in the presence of a positive internal control in nonneoplastic cells were considered negative. If staining was equivocal (eg, absent nuclear staining but no internal control), staining was repeated on whole sections. Loss of BAP1 expression was found in only 1 of 395 (0.3%) serous carcinomas but in 6 of 9 (67%) abdominal mesotheliomas (P < .001) and 131 of 277 (47%) thoracic mesotheliomas (P < .001). We conclude that BAP1 loss occurs extremely infrequently in gynecologic and peritoneal serous adenocarcinomas, whereas it is very common in mesotheliomas including abdominal mesothelioma. Therefore, although positive staining for BAP1 cannot be used to exclude a diagnosis of mesothelioma, loss of BAP1 expression can be used to very strongly support a pathological diagnosis of abdominal mesothelioma over serous carcinoma.

Fumarate Hydratase-deficient Uterine Leiomyomas Occur in Both the Syndromic and Sporadic Settings.

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome secondary to germline fumarate hydratase (FH) mutation presents with cutaneous and uterine leiomyomas, and a distinctive aggressive renal carcinoma. Identification of HLRCC patients presenting first with uterine leiomyomas may allow early intervention for renal carcinoma. We reviewed the morphology and immunohistochemical (IHC) findings in patients with uterine leiomyomas and confirmed or presumed HLRCC. IHC was also performed on a tissue microarray of unselected uterine leiomyomas and leiomyosarcomas. FH-deficient leiomyomas underwent Sanger and massively parallel sequencing on formalin-fixed paraffin-embedded tissue. All 5 patients with HLRCC had at least 1 FH-deficient leiomyoma: defined as completely negative FH staining with positive internal controls. One percent (12/1152) of unselected uterine leiomyomas but 0 of 88 leiomyosarcomas were FH deficient. FH-deficient leiomyoma patients were younger (42.7 vs. 48.8 y, P=0.024) and commonly demonstrated a distinctive hemangiopericytomatous vasculature. Other features reported to be associated with FH-deficient leiomyomas (hypercellularity, nuclear atypia, inclusion-like nucleoli, stromal edema) were inconstantly present. Somatic FH mutations were identified in 6 of 10 informative unselected FH-deficient leiomyomas. None of these mutations were found in the germline. We conclude that, while the great majority of patients with HLRCC will have FH-deficient leiomyomas, 1% of all uterine leiomyomas are FH deficient usually due to somatic inactivation. Although IHC screening for FH may have a role in confirming patients at high risk for hereditary disease before genetic testing, prospective identification of FH-deficient leiomyomas is of limited clinical benefit in screening unselected patients because of the relatively high incidence of somatic mutations.

Fibrous Pseudotumor of the Penis - An Unusual Finding During Repair of Fractured Penis.

Fibrous pseudotumors of the testis and penis are a rare phenomenon, forming a spectrum of heterogeneous lesions. To the best of our knowledge, there has been only 1 previous report arising from the penis. We present a case of fibrous pseudotumor of the penis, incidentally found during the surgical repair of a fractured penis. These benign lesions have been described in the literature and are most commonly referred to as pseudotumors. They should be distinguished from potentially malignant lesions, including fibrosarcomas, squamous cell carcinoma, and polypoid urothelial carcinoma. Being aware of this pathology is important to prevent unnecessary radical surgery.

von Hippel-Lindau syndrome.

von Hippel-Lindau (VHL) disease is an autosomal-dominant familial cancer syndrome associated with mutations of the VHL tumor suppressor gene (3p25-26). Its estimated incidence ranges from 1 in 36,000 to 1 in 53,000 with a penetrance of up to 95% by age 60. Genotype-phenotype correlation divides VHL into two broad clinical subtypes. Type 1 VHL is predominantly associated with large deletion or truncation mutations which result in an encoded protein with very little or no activity. It is associated with retinal and CNS hemangioblastoma and renal cell carcinoma but not pheochromocytoma. Type 2 is usually associated with missense mutations encoding a protein with limited activity and includes pheochromocytoma. It is further classified into three other subtypes (2A, 2B, 2C) based on the presence of hemangioblastoma and renal cell carcinoma. Visceral cysts in the kidney, pancreas and epididymis, nonfunctioning pancreatic neuroendocrine tumors which often show distinctive clear cell cytology, endolymphatic sac tumors and head and neck paragangliomas are well recognized but less common presenting features. Surveillance of carriers can reduce the burden of disease and is best performed in specialist referral centers with due consideration given to both the complex molecular pathogenesis and psychosocial aspects of the disease.